The present invention is generally directed to processes for the preparation of resin coated particulate materials, for example, carrier particles for use in two component xerographic developers. More specifically, the present invention relates to improved coating processes for the preparation of polymer coated carrier core particles.
Dry polymer coating processes for carrier particles are known in the art, reference for example, the aforementioned commonly owned U.S. Pat. Nos. 5,015,550, and 4,935,326.
The aforementioned references are incorporated in their entirety by reference herein.
In polymer particle coating processes of the prior art, various significant problems exist, for example difficulties in predicting or controlling, for example, the tribo and conductivity of the carrier. Some of the prior art coatings have a tendency to separate from the core in the form of chips or flakes. These flakes can have an adverse effect on the triboelectric charging properties of the developer. Another problem is fluctuations in the charge characteristics with changes in the relative humidity.
These and other disadvantages are avoided, or minimized with the coating processes of the present invention.
There remains a need for simple and economical coating processes for the preparation of resin coated carrier core particles wherein the resulting resin coated particles possess superior performance properties, such as tribo charging and durability, when used in, for example, two component developers.
The processes and products of the instant invention are useful in many applications, for example, including toner resins used for electrophotographic imaging processes, particularly color imaging, and for use, for example, in thermoplastic films and coating technologies.